Barking drums



A ril 23, 1963 A.-G. SANDISON BARKING DRUMS Filed Oct. 23, 1961 IN VENTOR ,0 6 BARKING DRUMS Alexander, omewame sandis'on, '546 14;}; s w., .Q r l Sound, nt m a Filed Oct. 23,1961, Ser. o. 146,89 2 Claiins. or. 144-203 This invention relates to barking drums of the type used for removal of bark from pulpwood logs, the logs being tumbled within the rotating drum to an. extent sufficientto remove the bark by attrition. Such drums are rotated by Suitable means about a horizontal axis, and non rotating vertical dams are locatedv at their. ends to retain the logs within the interior of the drum. The present invention relates to the drum itself and is. not concerned with such ancillary equipment as may be used in conjunction with it.

Barking drums have been constructed in the form of a cylindrical shell of plate mounted within external trunnion rings and. provided with gaps or openings for the discharge of bark. With such constructions, however, the' -contactjof the logs against the interior of the drum is of little utility for bark removal, as such contact occurs chiefly at the ends of the logs, Moreover, as the. shell is m'oulnted' inside the trunnion rings, the outside diameter of the latter is necessarily m uch larger thanthe inside diameter of the drum, as the trunnion rings have, to be of substantial cross-section to resistthe bending moments to which they are subject.

In the present invention the interior of the drum is circu-mferentially ridged so that contact may be obtained between the sides of the logs and the ridges, and in the preferred construction the cross-sections of the trunnion rings extend inside the shell to form at least a proportion of the ridges, thus also reducing the trunnion ring diameter necessary for a given internal drum diameter. Additional advantages realized by these and other features of construction will become evident as the specification proceeds.

The invention is exemplified in the accompanying drawings whereof:

FIG. 1 is a side elevation of a barking drum, partly in section, to show the interior.

FIG. 2 is a sectional view on the line 11-11 of FIG. 1, the direction of rotation being indicated by an arrow.

FIG. 3 is a fragmentary sectional view showing on an enlarged scale a detail of the construction shown in FIG. 1.

FIG. 4 is a fragmentary sectional view showing a detail of a construction alternative to that shown in FIG. 3.

Referring to the drawings, the greater part of the drum surface consists of courses of shell plate 1, which are attached to trunnion rings 2 and to an intermediately located toothed drive ring 3. The attachment between the courses of shell plate and the rings is located at the sides of the rings so that the inner portions 4 and 5 of the trunnion and drive ring cross-sections respectively form annular ridges projecting into the interior of the drum. The ridges are shown shaped with sloping sides and sharp apex, except in FIG. 4, where the alternative of a rounded apex is illustrated. Additional annular ridges 6, which may be formed of bent angle section welded to the shell, are shown at intermediate locations. End rings 7 serve to strengthen the ends of the drum.

Longitudinal lifters 8 are located in the shell and these lifters are provided with outlet passages 9 leading from the interior to the exterior of the shell for the passage of loosened bark. The inner ends of these passages are located on the leading sides of the lifters.

In the detail shown in FIG. 3 the ring 3 and shell courses 1 are formed with matching registers 10 and joined by welds 11 and 12. In the alternative detail 3,086,569 Patented Apr. 23, 1963 ice shown in FIG. 4 one of the shell courses 1 is provided with a flange 13, and this flange and the ring 3 are. machined with matching registers 14 and joined by studs 15 and nuts 16.

It will be. understood that thetrunnion rings 2 are for the rotatable mounting of the drum and are suitable for running on rolls in accordance with established practice. Rotation may be effected by a power operated pinion or chain engaging the drive ring 3. Alternatively a rollfriction drive may be employed, and'in this case the drive ring 3 may be dispensed with.

When a barking drum with its charge of logs is rotated the logs tend to adopt an interlaced pattern with the individual logs aligned in more or less random directions. When a plain cylindrical shell is employed, the logswill, for the most part, make. contact with the shell at their ends only, owing to the curvature of the shell, and. only those logs lying in a substantiallylongitudinal direction are likely to have their sides in contact with the shell; In such conditions the contact; of the logs with the shell is of little assistance in bark removal and may haveian injurious effect by damaging or'brooming the ends of the logs. In the present invention a large proportion ofthe logs will make. contact ontheir sides with at least one of the annular ridges 4, 5-; and 6, and the. pressure and movement ofthe sides of thelogs against the apices of the ridges contributes to bark removal, and, if required, cutting action may be obtained by leaving the apices sharp. The sloping sides of the ridgesprevent the possibility of, logs becoming wedged-between the ridges. An additionalv advantage is that the logs are, to a considerable extent, supported clear of the shell, allowing a relatively, free path for loosenedbark to slide down the rip-running side of the drum to the'outlet passages 9.

As the shell courses 1 are attached to the sides of the trunnion rings 2, a relatively large internal shell diameter is obtained for a given trunnion ring diameter, while still using a trunnion ring cross-section of ample depth to resist the bending moments to which it is subject. This is of practical importance, as experience has proved that a large internal diameter is conducive to efiicient bark removal, while the permissible outside diameter of the trunnion rings is often limited by transport or other considerations. Another advantage is that the junctions of the she-ll courses 1 to the trunnion rings 2 are comparatively close to the neutral axis of the cross-section of the latter, so that Welding employed at the junctions is remote from the more highly stressed portions of the cross-section and therefore less 'likely to be subject to fatigue cracking.

While reasonably satisfactory tumbling movement of the logs can be obtained even in a cylindrical drum of smooth interior provided that the level of the logs is kept suffic-iently high, it is found that the use of a limited number of Widely spaced lifters (preferably not more than four to a circle) intensifies the rubbing or churning movements of the logs with benefit to rapid hark removal. By staggering the angular positions of the lifters 8 in different courses of the drum, as shown in FIG. 1, a beneficial tendency to weaving axial movement of the logs is introduced, and the driving torque required for the drum is rendered more uniform than would be the case were the lifters in continuous longitudinal alignment. The lifters 8 are preferably made as substantial steel castings so as to minimise the danger of fatigue cracking occurring at the passages 9 under the pounding of the logs. The openings are formed entirely within the steel castings so that no plate edges are exposed, so that the danger of fatigue cracks, such as are liable to occur at exposed plate edges, is thus minimised. Location of the inlets of the passages 9 on the leading side of the lifters pro motes easy exit for the loose bark sliding down the uprunning side of the shell.

Barking drums are usually too large in size to permit the trunnion rings to be machined after completion of fabrication, and in many cases they are also too large to be shipped to their operating site as a completed unit. With the present design the preferred method is to build the drum in two or more annular sections with machined registration to permit completion of the assembly on the operating site without appreciable loss of accuracy. In the construction shown in FIGS. 1 and 3 the inner shell courses are joined to the previously machined trunnion rings 2, and their rims are then machined with registers 10 true with the trunnion rings. The drive ring 3 is machined with matching registers, and final assembly is made by completing welds 11 and 1'2. With the alternative construction shown in FIG. 4 a flange 13 is secured to one of the shell courses, and matching registers 14 are made, using the same general procedure as described above. The final joining of the sections is then made by studs 15 and nuts 16. It will be understood that it is not important for the end courses of the shell and their attached end rings 7 to run true within a high degree of precision, and these may be attached to the machined components at any convenient stage in the sequence of manufacture.

In FIG. 4 the ridge 5 is shown with a rounded apex. This may be preferred to the use of a cutting edge when de-barking logs of a type having soft bark.

What I claim as my invention is:

1. A rotary barking drum for de-barking pulpwood logs or the like comprising two trunnion rings, an intermediate ring machined on both sides with registers for location, two end courses of substantially cylindrical form each secured at its inner end to the outer side of a trunnion ring, two intermediate courses of substantially cylindrical form each secured at its outer end to the inner side of a trunnion ring and having its inner end machined with a register true with the trunnion ring and shaped to match the register on one side of the intermediate ring, and securing means to attach the inner ends of the intermediate courses to the sides of the intermediate ring after mating the locating registers, the rings having an inner diameter of less size than that of the shell courses so that the inner portions of the rings form annular ridges projecting within the interior of the drum and of sufiicient height to be capable of exerting efiective bark-stripping action on the middle portions of the logs as the logs are tumbled at random by the rotation of the drum.

2. A rotary barking drum comprising a plurality of shell courses of substantially cylindrical shape and rings having an inner diameter of less size than that of the shell courses, said shell courses being secured to said rings at the sides thereof, each course consisting of a plurality of arcuate plate sectors alternating with lifter members welded thereto, the lifter members being in the form of substantial castings having slots therethrough leading from the interior to the exterior of the drum, the slots being formed entirely within the castings.

References Cited in the file of this patent UNITED STATES PATENTS 1,070,092 Wright et a1 Aug. 12, 1913 1,136,959 Hockley Apr. 27, 1915 1,655,628 Royem Jan. 10, 1928 2,592,054 Mertz et al Apr. 8, 1952 2,688,350 Waller Sept. 7, 1954 2,712,330 Thompson July 5, 1955 2,897,858 Hanson Aug. 4, 1959 2,943,656 Wakeman July 5, 1960 3,020,943 Hjartsater Feb. 13, 1962 FOREIGN PATENTS 719,155 Germany Apr. 11, 1942 

1. A ROTARY BARKING DRUM FOR DE-BARKING PULPWOOD LOGS OR THE LIKE COMPRISING TWO TRUNNION RINGS, AN INTERMEDIATE RING MACHINED ON BOTH SIDES WITH REGISTERS FOR LOCATION, TWO END COURSES OF SUBSTANTIALLY CYLINDRICAL FORM EACH SECURED AT ITS INNER END TO THE OUTER SIDE OF A TRUNNION RING, TWO INTERMEDIATE COURSES OF SUBSTANTIALLY CYLINDRICAL FORM EACH SECURED AT ITS OUTER END TO THE INNER SIDE OF A TRUNNION RING AND HAVING ITS INNER END MACHINED WITH A REGISTER TRUE WITH THE TRUNNION RING AND SHAPED TO MATCH THE REGISTER ON ONE SIDE OF THE INTERMEDIATE RING, AND SECURING MEANS TO ATTACH THE INNER ENDS OF THE INTERMEDIATE COURSES TO THE SIDES OF THE INTERMEDIATE RING AFTER MATING THE LOCATING REGISTERS, THE RINGS HAVING AN INNER DIAMETER OF LESS SIZE THAN THAT OF THE SHELL COURSES SO THAT THE INNER PORTIONS OF THE RINGS FORM ANNULAR RIDGES PRO- 